title: First artificial hybrid of the eel species Anguilla australis and Anguilla anguilla.
abstract: BACKGROUND
  Studies on artificial hybridization of different Anguilla species were conducted recently, i.e. female A. australis with male A. dieffenbachii, and female A. japonica with male A. anguilla. The existence of these artificial hybrids was however not demonstrated by independent genetic methods. Two species - A. anguilla and A. australis - that are phylogenetically close but have different sexual maturation times (12-25 weeks and 6-8 weeks, respectively), were expected to produce favourable hybrids for reproduction studies.
  
  
  RESULTS
  A modification of the protocol for the reproduction of Anguilla japonica was used to produce eight-day Anguilla australis larvae, with a success rate of 71.4%. Thus ten out of 14 females produced eggs that could be fertilized, and three batches resulted in mass hatching. Hybrid larvae from female A. australis x male A. Anguilla survived for up to seven days post fertilization (dpf). The early development of the hybrid showed typical characteristics of A. anguilla tail pigmentation at 50 hours post fertilization (hpf), indicating expression of genes derived from the father.
  
  
  CONCLUSIONS
  In this paper we describe the first production of hybrid larvae from male A. anguilla and female A. australis and their survival for up to 7 dpf. A species-specific nucleotide difference in the 18 S rDNA gene confirmed that genes from both A. australis and A. anguilla were present in the hybrids. The developmental stages of the hybrid eel embryos and larvae are described using high resolution images. Video footage also indicated a heart beat in 5-dpf larva.
authors.affiliation: ZF-screens BV, Niels Bohrweg 11, 2333 CA Leiden, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: Burgerhout
authors.forename: Sebastiaan A
authors.initials: SA
authors.lastname: Brittijn
authors.forename: Tagried
authors.initials: T
authors.lastname: Kurwie
authors.forename: Paul
authors.initials: P
authors.lastname: Decker
authors.forename: Ron P
authors.initials: RP
authors.lastname: Dirks
authors.forename: Arjan P
authors.initials: AP
authors.lastname: Palstra
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.forename: Guido E E J M
authors.initials: GE
authors.lastname: Van den Thillart
mesh_terms: D000811:Anguilla / Q000196:embryology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D000818:Animals; D002678:Chimera / Q000033:anatomy & histology / Q000196:embryology / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D018507:Gene Expression Regulation, Developmental; D006824:Hybridization, Genetic; D007814:Larva; D008297:Male; D010062:Ovulation Induction; D016133:Polymerase Chain Reaction; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012098:Reproduction; D017422:Sequence Analysis, DNA
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S